Printing-press



(No Model.) 2 Sheets-Sheet 1.

G. WILLIAMSON.

' PRINTING PRESS.

No. 276,517. Patented M31324, 1883.

afia): X w aevge7/fZia'rmaow %d gywwyw (No Model.) 2 Sheats-Sheet 2.

G. WILLIAMSON;

. PRINTING PRESS. Patented Apr.24, 1883.

UNITED STATES PAT NT OFFICE.

GEORGE WILLIAMSON, OF CAMBRIDGE, ASSIGNOR OF ONE-HALF TO \VAL- TER G. CHASE, OF BROOKLINE, MASSACHUSETTS.

PRINTING-PRESS.

SPECIFICATION formingpart of Letters Patent NO. 276,517, dated April 24, 1883,

Application filed October 19, 1882.

To all whom it may concern:

' Be it known that I, GEORGE WILLIAMSON, of Cambridge, county of Middlesex, State of Massachusetts, have invented an Improvement in PrintingPresses, of which the following description, in connection with the accompanying drawings, is a specification, like letters on the drawings representing like part-s.

My invention relates to printing-presses, it being embodied in a press of that class in which the sheet to be printed is laid upon a tympan forming the face of the platen by which the sheet to be printed is pressed against the type. The tympan, which consists of a sheet of cloth, paper, or parchment, is usually held in place upon the surface of the platen by means of two clamps engaging opposite edges of the sheet and holding them by friction between the said clamps and the adjacent edges of the platen. When a press is used for a long time with a tympan arranged in this manner, the tympan becomes loose and rises up from the surface of the platen, thus causing great inconvenience.

My invention consists partly in the combination, with the platen and tympan, of a takeup roll for the said tympan, wherebyit may be drawn tight at any time.

The invention also consists in certain details of construction by means of which the tympan,

with its take-up roll, may be readily removed when desired. The platen is shown as provided with a chase-holding device for the purpose hereinafter described.

Figure 1 shows in perspective a press'platen provided with a tympan and take-up roll in accordance with this invention. Fig. 2 is a detail, showing on a larger scale the end of the edge 2 of the tympan between it andthe rear.

end of the platen. The tympans I) have usually been fastened at the front edge, 4, of the platen by another clamp similar to the one o by which the edge 2 of the tympan is fastened; but when held in this way the tympans, after (No model.)

I considerable use, become stretched and loose,

and it is diflicult to tighten them by means of the clamps c. To obviate this difficulty the forward end of the tympan b is carried over the edge 4 of the platen and connected with a take-up roll, (I, mounted to rotate in bearings ef, suitably attached to the platen a. The said take-up roll is provided with aratchet,g,which,

in co-operation with a pawl, h, mounted on the hearing piece 0, prevents the backward rotation of the roll and consequent loosening of the tympan. The end d of the arbor of the roll 61 is shown as squared or otherwise adapted to be engaged by a key or wrench, by which 65 it may be rotated to give the tympan b the proper tightness, and by which, after the tympan has become stretched or loose by use, the said roll may be turned slightly the space of one tooth, for instance-on the ratchet 9, so as to make the tympan tight again without materially changing its adjustment in relation to the platen. One or both the bearing-pieces e f is made sufficiently flexible to yield laterally,

as shown in dotted lines, Fig. 1, so as to en- 5 able the adjacent end of the arbor of the takeup roll at to be disengaged therefrom, when the other end of the said arbor may be removed longitudinally from the correspondingbearin g,

e, and the tympan, together with the take-up roll, removed from the press, the clamp 0 being then released in the usual manner. The strain brought to bear on the tympan-sheet by means of the take-up roll 61 may be so great that the clamp c, if held only by friction, would be 8 raised from the adjacent edge of the platen, and would then release the end 2 of the tympan. This is obviated by the fastening device, shown as screws 5 entering the platen a, and having their heads properly located to overhang the adjacent portion of the clamp c and prevent the said clamp from turning on its pivot 3 to release the edge 2 of the tympan. A portion of the heads of the said screws is removed,

as shown at 5, so that by turning the screw to 5 bring the said portion 5 parallel to the edge of the clamp c the said clamp will be free to move for the purpose of fastening or releasing the edge 2 of the tympan in the usual manner.

In small job-presses, in which the bed is usu- 1o:

ally substantially vertical and the platen moves therefrom toan inclined position to receive the paper to be printed,it is often necessary to remove the chase containing the type in order to obtain access to the bed. The chase has usually to be set aside upon the floor, where it is more liable to be accidentally disturbed, and it is, moreover, a matter of some difficulty to remove the heavy chase from the press. This difficulty I have obviated by providing the platen a with a chase-holding device, shown as strong hooks m placed at the front thereof in proper position to receive the lower edge of the chase when the platen is in its position most remote from the bed of the press. The said chase-holding device m thus supports the chase in' a safe place comparatively near to the bed, so that it has to be moved but a short dis tance, and in thus moving it 1 have been accustomed to employ a counterbalancing-weight, w, connected with one end of a cord, y, passing over a pulley above the press, and provided with a hook, z, to engage the chase, so that its Weight will be partially or wholly counterbalanced by the weight at the other end of the -c0rd,and it may very easily be swung from its position into the bed to the receiving-hooks m.

I claim 1. The platen and tympan, combined with the pivoted clamp and its locking device for one end of the said tympan, and the take-up roll with its ratchet and pawl connected with the other end of said tympan, substantially as and for the purpose described.

2. The combination of the platen of a printing-press with a chase-holding device connected therewith, substantially as described.

3. The platen, tympan, and clamp for one end thereof, combined with the take-up roll and its bearings mounted on the said platen and arranged to yield, as described, whereby the tympan, with its roll, may be detached from the platen, substantially as described.

In testimony whereofl have signed my name to this specification in the presence of two subscribing witnesses.

GEO. WILLIAMSON.

Witnesses O. B. GRAVES, A. H. NAsoN. 

